In deep water the closing mechanism is usually actuated by a screw propeller which begins to work when the line is being hauled in and can be set so as to close the waterbottle in a very few fathoms. A small but heavy water-bottle has been devised by Martin Knudsen, provided with a pressure gauge or bathometer, by which samples may be collected from any moderate depth down to about roc fathoms, on board a vessel going at full speed.
The boiler pressure gauge measures the pressure of the water forced through the espresso.
If possible, take along a friend and listen for noises, check knobs and controls to make sure they work, and bring along a tire pressure gauge to check the tires.